April 19 – Soda Pops!

The only thing better than science is science that ends up making a huge mess. In today’s installment of the Secret Science Society, Mary, Daniel, and Peter discover exactly why candy plus soda pop makes such a big mess in Soda Pops!


As was normal for a Saturday morning, the Secret Science Society was in the backyard, making a mess. And the mess was everything that they had hoped it would be. Taking turns, Mary, Peter, and their friend Daniel would each open up a bottle of soda and then drop several small candies into it and quickly jump back to avoid the geyser of foam spewing out of the bottle.

“This is great!” Peter enthused. “I wish we had more soda!”

“That would be fun, but I wish we knew why it worked,” Daniel said.

“Me, too,” Mary replied. “Why does adding candy to soda make it spurt out like that? A scientist would know how to figure it out!”

At that moment, a voice from behind them called out “Then it is a good thing that you are all scientists, isn’t it?”

“Hi, Mom!” Peter said. “Taking a break from the cosmos?”
“Yes; I’ve found enough new planets for this week.” Peter’s mother studied planets around other stars and did most of her work at home. “I decided to come out and see what all the squealing was about.”

“We’ve been making soda fountains,” Mary said. “But we can’t figure out why it happens.”

“Well, let’s think about this,” Peter’s mother replied. “What goes into the reaction?”

“Carbonated soda and candy,” Daniel said.

“And we get foam and a lot of carbon dioxide out,” Peter added.

“OK, so we have to decide what it is about the candy that makes the carbon dioxide come out so quickly. What is the candy made up of?”

“It is mostly sugar with some mint flavor,” Mary said.

“And is the candy smooth or is it rough?”

Daniel peered closely at one of the candies in his hand. “It is sort of rough on the outside; there are lots of little bumps and holes on it.”

“Then we’ve got three possibilities,” Peter’s mother said. “First, it could be that the mint oil makes the reaction happen. Second, it could be that the sugar makes it happen. Third, it could be that the candy’s rough outside makes it happen. How can we find out the answer?”

“We could put a little oil into a bottle of soda,” Peter said. “If it makes the soda fountain out, then we’ve found the answer.”

“And we could try adding sugar to soda,” Daniel added. “If it makes the soda fountain out, then we’ve found the answer.”

“And we could add something that isn’t sugar but looks like it to the soda,” Mary concluded. “If the soda boils out then we know that it isn’t sugar that makes it go. But what has rough edges like sugar?”

“Salt does,” Peter said. “Let’s try it and see what makes the soda go!”

Eagerly, the three ran into the kitchen to gather up the supplies that they’d need. Daniel grabbed a bowl of sugar. Mary picked up a salt shaker. And Peter rummaged in the pantry until he found the oil. The friends then went back outside to run their experiment.

What do you think will happen? Do the experiment!

“Me first!” Peter said. He grabbed a soda bottle and took off its cap before setting it back on the ground. He carefully poured a little oil into the bottle and moved back.

“Nothing’s happening!” Daniel said. “It must not be the oil in the candy. Let’s try the sugar.” He opened a second bottle of soda and set it on the ground. He poured in some sugar and jumped back to avoid the rush of foam. “Aha! It’s the sugar!”

“Don’t jump to conclusions,” Mary said. “Let’s see what happens with the salt.” Mary took her turn opening a bottle of soda and then added salt to it. Again the soda fountained out of the bottle.

“So it isn’t sugar that makes it work,” Peter said. “I guess we should have known that because soda with sugar doesn’t spray out of the bottle.”

“Not unless you shake it up,” his mother said. “What happened is that both salt and sugar have a lot of rough edges; you can see them in a magnifying glass if you look. Those edges give the carbon dioxide a place to come out of solution.”

“Neat!” Mary said. “So anything with rough edges will make it work?”

“That’s right,” Peter’s mother replied. “If you look carefully at a glass with soda in it, you will see that there is often a stream of bubbles coming form a place on the glass. That’s where the glass has a small crack or a bit of something stuck on it. Scientists call those nucleation points. The more nucleation points there are, the more gas that can come out of solution.”

“But why do the bubbles come out at the edges?” Daniel asked.

“The exact reasons aren’t known yet,” she replied. “We know that part of the reason is because water molecules like to stick together; we call that surface tension. At a nucleation point, the water sticks to itself and not the glass or sugar or whatever. But the gas doesn’t stick together, and fills the gap. That pushes the water back a little, which lets more gas into the area. The reaction feeds on itself and you get a bubble that is too big to stay in place so it floats up and a new one starts. Do it fast enough by having lots of nucleation points and you get…”

“A soda fountain!” Mary exclaimed.

“OK,” Daniel said. “That makes sense. But why does diet soda work better?”

“That’s because of another effect,” Peter’s mother explained. “The sweetener in diet soda makes the water molecules stickier so that they make strong bubbles. That lets the foam hold together, which makes it go higher. But you could do the same thing by adding some glycerine and soap to a regular soda.”

“Yuck! I sure wouldn’t want to drink that!” Mary exclaimed.

“Me neither!” Peter’s mother replied. “But I would like to have some fun.”

Grabbing the candy, she turned to the soda to make her own fountain.

April 20 – Big Bang

Today’s Factismal: The American Chemical Society is 138 years old today.

The late 1800s was an exciting time for chemistry. In 1869, Mendeleev created the periodic table and used it to predict the existence of several new elements. More than 26 new elements had been discovered since 1850. Aluminum had moved from being more expensive than platinum to being cheaper than tin. And on April 20, 1876, a group of thirty-seven chemists came together for the first official meeting of the American Chemical Society.

Today there are 163,000 members of the American Chemical Society. They work in many industries, from medicine to aerospace to oil and gas to agriculture, and earn starting salaries of about $80,000 a year. They work in many places from the thermal springs of Yellowstone to the labs of NASA to sampling stations in Antarctica to product development teams in Detroit. And they work with chemicals as safe as HOH and as exciting as FOOF. In short, chemistry is a great career.

If you’d like to see what it is like to be a chemist, then why not visit ChemSpider? It’s a free, open-source database of chemical structures and other information:

April 18 – Hot in here

Today’s Factismal: The first estimate of how Earth’s temperature would change with increased CO2 was made 118 years ago today.

There are very few scientific discoveries that are as misunderstood by the public or as unfortunately politicized as the effects of carbon dioxide on temperature. Though the basic effect was first described in 1859, it wasn’t until 1896 that Svante Arrhenius realized that changing the amount of carbon dioxide in the atmosphere could change the global temperature. And it wasn’t until a century later that the results of their work would become politicized.

The way that CO2 works has nothing to do with how greenhouses work; unfortunately, because Svante used a greenhouse as an analogy in his paper, we are stuck with calling it “the greenhouse effect”. (The lesson here is that you should always be careful with your analogies.) But in order to understand the greenhouse effect, you need to understand both heat and light. Fortunately, the two are related.

The hotter the object, the shorter the wavelength of light it emits (Image courtesy LED.com)

The hotter the object, the shorter the wavelength of light it emits
(Image courtesy LightEmittingDiodes.org)

We know that light isn’t limited to what we can see. Instead, it spreads across a wide spectrum that extends from photons with kilometer lengths (radio waves) through light with centimeter wavelengths (microwaves) and light with micrometer wavelengths (infrared light) to light with angstrom wavelengths (visible light) and light with wavelengths shorter than a molecule (ultraviolet light) and even light with wavelengths small enough to fit inside an atom (X-rays). But what is truly nifty about the wavelength of light is that it is a direct measurement of the amount of energy it has; the shorter the wavelength, the more energy.

So ultraviolet light is ultra-violent when compared to visible light which itself is more energetic than infrared (in-da-bed) light. And only things that are very hot (which is the same as saying very energetic) can make photons that are energetic. Cool things make photons with long wavelengths and hot things make photons with short wavelengths.

Now let’s apply this to the Earth. When sunlight, which is rich in visible and ultraviolet light because of the Sun’s temperature, shines on a planet, the planet absorbs the light and heats up. As the planet’s temperature goes up, it starts to emit light. But, because the planet is cooler than the Sun, it gives off light at longer wavelengths. The visible and ultraviolet light of the Sun is transformed into infrared light. We can calculate just how hot the planet should be using an ideal case known as a blackbody and get a blackbody temperature. (Sound complicated? It is as easy as using an ear thermometer, which is based on the same idea.) But the Earth, Venus, and Mars are all hotter than they should be.

The increase in global temperature is driven in large part by the increase in CO2 (Image courtesy NOAA)

The increase in global temperature is driven in large part by the increase in CO2
(Image courtesy NOAA)

The reason for that is because of CO2. CO2 happens to be opaque in IR; that is, it blocks some of the “heat radiation” given off by the Earth. This is reabsorbed by the atmosphere, raising its temperature slightly. Of course, lots of other factors come into play when you are talking about a planet , so the temperature change isn’t instantaneous and it has some wiggles in it. But overall, the pattern is clear: increasing CO2 increases temperature and changes climate.

If you’d like to learn more about the effects of CO2 and what you can do to help, then why not look at the MIT Climate CoLab?


April 17 – Method to the madness

Today’s Factismal: Earth is the only planet that does not have a system for naming its features.

If you’ve ever looked at the Moon or at pictures of Mars or the other planets, then you’ve probably noticed that there is a peculiar rhythm to the names. For example, all of the large, dark blotches on the Moon are called “Mare Something” (Mare Frigoris, Mare Tranquilitatis, Mare Insularum) and all of the craters are named after scientists and explorers (DaVinci Crater, Tycho Crater, humboldt Crater). Similarly, all of the features except one on Venus are named after women. And all of the moons of Jupiter are named after the many,, many paramours that Jupiter (Zeus) had.

Scientists use these conventions because it makes it easier to remember both what you are looking at and where it is. “Maat mons? That’s an Egyptian goddess so it must be a mountain on Venus.” “Rhea? That’s one of the titans, so it must be a moon of Saturn.” But what even scientists sometimes forget is where the system got its start.

The Moon, with Mare Imbrium and Mare Frigorum clearly visible (My camera)

The Moon, with Mare Imbrium and Mare Frigorum clearly visible
(My camera)

It all happened in 1665, just 33 years after Galileo had been convicted of heresy for promoting the idea that the Earth moved around the Sun instead of the other way around. A Catholic priest by the name of Giovanni Riccioli who was a fan of Galileo’s methods but not of his ideas was busy using the telescope (which Galileo invented) to look at the Moon. He agreed that Galileo was right when he said that the Moon’s surface wasn’t perfect; that it was covered with blotches and pockmarks. And the thought that Galileo was wrong when he said that the Earth went around the Sun (Giovanni, like all good Jesuits at the time, held that things were the other way around). But how could the new features on the Moon be described to other astronomers across the globe? With a map.

So Giovanni spent quite a few late nights staring at the Moon and drawing a detailed map of its surface. But Giovanni wasn’t satisfied to just make a pretty image; instead, he wanted to provide a way for people to know that they were all talking about the same thing when they said “that big bright blotch on the bottom left”, so Giovanni named the things that he saw on the surface of the Moon. Because the big dark blotches looked like they were full of water (spoiler: they weren’t), he named them “mares”, which is Latin for “seas”. And he named the different seas after the different nymphs. He then named the smaller dark blotches after lakes (“lacus”), inlets (“sinus”), and marshes (“paludes”).  So by looking at the first part of the name, a scientist will always know about how big the object is. And by looking at the second part, a scientist has an idea of where on the Moon it is.

Giovanni then went a step further and named the craters that he could see. But, being a Jesuit, he had to include a little joke in the names. Just as Michelangelo painted his enemies in Hell, Giovanni used the names of those who supported the heliocentric universe for the craters nearest Oceanus Procellarum (the largest of the mare and the only “oceanus” or ocean on the Moon); if you don’t get the joke, it is because you haven’t yet realized that Oceanus Procellarum means “Ocean of Storms”.

Though Giovanni named as many of the features as he could see, his telescope wasn’t very good. But today, we have much better telescope and even spacecraft orbiting the Moon, sending back lots of high quality pictures of the surface. And you can use those images to identify and name things on the Moon. If you’d like to take part, then head on over to the Moon Zoo:

April 16 – Nest Egg

Today’s Factismal: Gentoo penguins and chinstrap penguins make nests out of pebbles so that rain and melting snow can drain out of the nest.

The problem with being a bird that lives in Antarctica is that there aren’t very many trees. Actually, there aren’t any trees at all; the vegetation is mostly mosses and lichens with the occasional blood algae for color. That’s a problem because birds use trees to hide from predators and, more importantly, to build nests that will protect their eggs.

A Gentoo penguin on his nest of pebbles (My camera)

A Gentoo penguin on his nest of pebbles
(My camera)

Fortunately for the penguins in Antarctica, there aren’t very many predators on the land (in the water is another matter). But they still need to protect their eggs. Some penguins, such as the Emperor penguin, use their feet. For 64 days, the proud papa balances the egg on his feet until the chick finally hatches. Even after that, the parents will take turns holding the chick on their feet until it is large enough to survive on its own.

A Chinstrap penguin protecting her chick (My camera)

A Chinstrap penguin protecting her chick
(My camera)

But most penguins aren’t willing to sit in one place while balancing an egg on their toes for two months. They crave a better life. And they get it by building nests. And, for the most part, those nests are built out of pebbles. Though cold and pointy, pebbles offer one indisputable advantage to nests built out of clay (like those of the ovenbird) or spittle (like those of the swift) or dug into the sand (like those of the kingfisher) – pebbles drain. And when you live in a climate as wet as the coast of Antarctica, you need a nest that will drain.

Pebble stealing is a common activity (My camera)

Pebble stealing is a common activity
(My camera)

Though you may not be able to go to Antarctica to observe a penguin nest, you can help scientists by looking for bird’s nests in your own neighborhood. The folks at NestWatch need your help to locate and identify nests across the globe – so why not flock together with them?

April 15 – A little squirrely

Today’s Factismal: Gray squirrels in forests live about six years but most gray squirrels in cities live less than one.

The earliest example of a squirrel showed up more than 40 million year ago. Looking a lot like a modern flying squirrel (but with no moose to keep it company), the early squirrel got the acorn and soon diversified. Today there are 285 different species of squirrel, spread over six continents. It used to be five, but then someone decided that Australia needed squirrels.

A squirrel at lunch (Image courtesy Laughing Squid)

A squirrel at lunch
(Image courtesy Laughing Squid)

Most squirrels feed on plants with occasional bouts of nibbling on insects, slugs, and small birds and snakes. Because they cannot digest cellulose, squirrels prefer the same parts of plants that we do: leaves, buds, nuts (including acorns), and fungi. But unlike people, squirrels have a lot of things that like to feast on them, such as snakes, birds, raccoons, and automobiles to name but three.

And that last predator is why a gray squirrel in an urban environment typically lives less than a year even though the same squirrel would last for six years in a forest. The jerky, back and forth evasion pattern that gray squirrels have evolved to escape from predators in a forest makes it very hard to automobile drivers to avoid hitting the poor beast. As a result, the leading cause of death for gray squirrels in a city is being run over.

A smug grey squirrel with bird food he stole from my feeder (My camera)

A smug gray squirrel with bird food he stole from my feeder
(My camera)

Fortunately for the species, they are exceedingly prolific breeders. A gray squirrel becomes sexually mature at six months and a female can have two litters of two to six baby squirrels each year. As a result, even though they only live a short time, the species is in no danger of dying out. But they do provide biologists with a puzzle: where do they live? What do they eat?

And the biologists would like your help in solving the puzzle. All it takes is a pair of binoculars, a few hours, and a willingness to spy on our tree-dwelling neighbors. If you’d like to help, then why not join Project Squirrel?

April 13 – Lightning Fast

Today’s Factismal: The males of the lightning bug species Photinus carolinus will all flash in unison.

Imagine that you are in the Great Smokey Mountains, hiking along a trail at night. Suddenly, the trees come alive with hundreds of thousands of little lights, all flashing at the same time. You’ve just seen Photinus carolinus (“Light-maker from Carolina”) in action. These little lightning bugs are also called fireflies, even though they are neither bugs nor flies; they are beetles.

A firefly on a leaf(Image courtesy Museum of Science)

A firefly on a leaf
(Image courtesy Museum of Science)

There are over 2,000 species of fireflies, each of them has its own unique flashing pattern including not at all for several species. Only a very few patterns include flashing in unison; these optical chorus lines can be seen in the jungles of Malaysia, along the rivers of the Philippines, and in the forests of Tennessee and South Carolina. For most of the species, the light flash is a way for the one firefly to attract another in order to make more lightning bugs. But there are many fireflies that have a somewhat more insidious purpose; the female fireflies use the flashes to attract males of other species, whom they then turn into dinner.

Not all fireflies eat other fireflies. Many lightning bugs eat plants, pollen, nectar, insects, and even snails! About the only thing that they all do is glow as larvae. If you’d like to learn more about fireflies and help scientists track these lightning bugs, then why not join a firefly watch program?